The Sun tabloid last week published details of documents from Czechoslovakia's intelligence archives which, it said, showed Corbyn had met an agent three times in the 1980s. Other newspapers have repeated the claims.

In a social-media video Tuesday, Corbyn said the stories were being spread by rich media barons worried by the prospect of a left-wing Labour government.

Corbyn's office acknowledged that he had tea with a Czech diplomat, but said any claim he was "an agent, asset or informer for any intelligence agency is entirely false and a ridiculous smear."